radius 23 videos

Surface Area of Spheres
Geometry Volume
How to calculate the surface area of a sphere given a radius.
sphere surface area radius 
Radii to Tangents
Geometry Circles
How to define a tangent line; how to determine the angle a radius to a tangent forms.
tangent radius right angle point outside the circle perpendicular 
Area of Circles
Geometry Area
How to derive the formula to calculate the area of a circle.
circle radius circumference area 
Regions Between Circles and Squares
Geometry Area
How to calculate the area between a square and an inscribed circle.
shaded region square circle radius 
Equation of a Circle
Geometry Pythagorean Theorem
How to derive the equation for a circle using the distance formula.
distance formula radius center circle 
Equation of a Circle
Trigonometry Pythagorean Theorem
How to derive the equation for a circle using the distance formula.
distance formula radius center circle 
Circumscribed and Inscribed Circles and Polygons
Geometry Constructions
How to define circumscribed and inscribed circles and polygons relative to each other.
vertex radius polygon inscribed circle circumscribed 
Circumference
Geometry Circles
How to calculate the circumference of a circle.
circumference pi distance radius diameter ratio 
The Circle
Precalculus Conic Sections
How to use the distance formula to derive the equation for a circle.
circle center radius distance formula equation for a circle 
The Circle
Precalculus Equations of Lines, Parabolas and Circles
How to use the distance formula to derive the equation for a circle.
circle center radius distance formula equation for a circle 
The Circle
Algebra 2 Conic Sections
How to use the distance formula to derive the equation for a circle.
circle center radius distance formula equation for a circle 
The Ellipse
Precalculus Conic Sections
All about ellipses.
ellipse co vertices vertices major axis minor axis focus foci x radius y radius 
The Ellipse
Algebra 2 Conic Sections
All about ellipses.
ellipse co vertices vertices major axis minor axis focus foci x radius y radius 
Atomic Radii  Ionic Radii
Chemistry The Periodic Table
The periodic trend of atomic radii.
atomic radii ionic radii atomic radius ionic radius effective nuclear charge 
Volume of Cones
Geometry Volume
How to compare the volume of a cone and a cylinder and how to calculate the volume of a cone given the radius and height.
volume base area height circle area 
Parametrizing a Circle
Precalculus Vectors and Parametric Equations
How to write the parametric equations of a circle centered at (0,0) with radius r, oriented counterclockwise.
the unit circle cosine sine parametrization parametric equations circle counter clockwise 
Arc Length
Geometry Circles
How to define arc length and how it is different from arc measure; how to calculate the length of an arc.
arc length arc measure concentric circles fraction circumference radius diameter 
Area of a Sector
Geometry Area
How to derive the formula to calculate the area of a sector in a circle.
sector central angle intercepted arc circle radius area